1. Field of the Invention
The present invention relates to a method for manufacturing a tape guide employed for guiding the magnetic tape of a data cartridge, i.e., an external memory device of a computer.
2. Description of the Related Art
A conventional tape guide employed for guiding the magnetic tape of a data cartridge comprises a cylindrical portion for guiding the surface of the tape; and collar portions integral with the cylindrical portion and located at the respective axial ends of the cylindrical portion. The tape guide is made by working a cylindrical blank formed of a very hard stainless steel. The blank is first worked to have a predetermined shape and size by means of an ND lathe, and is then subjected to barrel finishing, quenching, diamond lapping, to thereby obtain a stepped pin to be used as a tape guide. After being subjected to heat treatment, the tape guide is provided with a hardness of approximately HV 500. The reason for using a very hard material as the material of the tape guide is prevent the magnetic tape from being scratched. (If the surface of the tape guide is not hard but soft, the magnetic tape is likely to be scratched.)
As described above, the conventional tape guide is made by working a blank formed of a stainless steel. In general, a stainless steel is hard to work, and the stainless steel used as the material of the blank is very hard, as mentioned above. Thus, the material cost of the blank is inevitably high, and the blank cannot be worked with ease. In addition, the conventional tape guide has a complicated shape since, as mentioned above, it is comprised of a cylindrical portion and axial-end collar portions integral therewith. Due to the complicated shape, the polishing of the conventional tape guide is laborious work. Therefore, according to the conventional tape guide-manufacturing method, not only the material cost but also the working cost is high, thus increasing the overall manufacturing cost of the tape guide.
Accordingly, it is a principal object of the present invention to provide a tape guide-manufacturing method which solves the problems of the conventional method and which permits a high-quality tape guide for use in a data cartridge to be manufactured at low cost.
To achieve this object, the present invention provides a method for manufacturing a tape guide which is to be arranged inside a data cartridge so as to guide a magnetic tape contained in the data cartridge, the method comprising the steps of:
preparing a cylindrical blank which is formed of a non-magnetic material and has a predetermined length and a predetermined diameter, and with which the main portion of the tape guide is to be made;
forming a step on the blank, thereby obtaining a stepped blank having a large-diameter portion and small-diameter portions located at respective ends of the large-diameter portion;
forming fine irregularities on the entire surface of the stepped blank;
electrically plating the blank having the fine irregularities with chromium, by rotating the blank in a plating liquid containing chromium ions, the electrical plating step including a sub-step of maintaining the temperature of the plating liquid approximately in the range of 50.degree. to 60.degree. C., and a sub-step of maintaining the current density approximately in the range of 40 to 50 A/dm.sup.2 ; and
forming a large number of minute grooves at least in the entire large-diameter portion of the blank plated with chromium, in such a manner that the grooves extend in the circumferential direction of the blank.
A data cartridge's tape guide manufactured in the method of the present invention withstands long use. In addition, it can smoothly guide the magnetic tape of the data cartridge and can be manufactured at low cost.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.